Drive for a roll to maintain constant web stress



Sept. 10, 1940. K. s. TISELIUS ET AL DRIVE FOR A ROLL TO MAINTAIN CONSTANT WEB STRESS Filed May 27, 1939 2 Sheets-Sheet l //1|/e/?2or Karl Gustav 7752 Has and Nz'lSJ-E.Ha 1' perfif/ornef Sept. 10, 1940. K. e. TI SELIUS ET AL 2,214,355

DRIVE FOR A ROLL T0 MAINTAIN CONSTANT WEB STRESS Filed May 27, 1939 2 Sheets-Sheet 2 PIX 2x l/2X f e /hver 1fors. Karl Gusiqrfiselcus" and A/zzSJEHQ ZQf W WQ - '15 of an electric machine acting. as generator.

Patented Sept. 1-0, 1940 ems FOR A ROLL 'ro MAINTAIN CONSTANT WEB STRESS Karl, Gustav Tiselius, Vasteras, Sweden, and Nils J. E. Hagliif, Wanstead, London, England, assignors to Allmanna Sve'nska Elektriska Aktiebolaget, Vasteras, Sweden, a corporation of Sweden Application May 27, 1939, Serial No.2'16,137

' In Sweden April 25, 1938 3 Claims.

The present invention refers especially to the drive of printing presses and has for its object an arrangement for-the maintaining of a constant stress in the paper'running through the printing press, but the invention is not limited to the drive of printing presses but can also. be applied in otherncases where it is necessary to run a ribbonor wire-formed material with a constant stress through a machine.

.In printing presses a suitable stress in the paper running through the press generally is achieved thereby that the'roll from which the paperis unwound, is braked one or other man- I ner. In many-cases this is achieved by the aid In order to avoid jerks in the paper due to the speed variations of the press the electric machine, whichis goiipled tothe roll from which the paper is unwound must be so regulatedthat the 20 periferal. speed of the roll becomes the same as the speed of the web in the press. The braking machine has previously beenregulated by means of a membegwhich has measured the tension in the paper. This member has previously generally 25 been a lever with aroll at'the end which has pressed against the web and caused a deflection in the web. The motions up and down of the roll due to the variations in the stress of the paper have been transmitted by the lever to the 30 member which has regulated the braking ma- Y chine.- It has, however, been shown by the practice that due to the large speed of the paper in modern printing presses and due to the large masses in modern printing presses such a regula- 35. tion,is not suflicien't because it acts too slowly. When the speed of 'the press suddenly changes the-member measuring the stress in the paper has not time enough to regulate thebraking elec-. -tric machine so that thestress in the paper will 40 often be so large that the paper is torn or becornes slack if the press is suddenly braked.

The present invention has for itsobjectan ar-I rangement for regulating the braking electric 1 Q machine which is distinguished'by a considerably connected with the brush displacement motor l9 i The action of the arrangement is the following:'

mentsand Fig. 3 'is'awhich shows the regulating operation of.the arrangement shown in Fig. 1. r

In Fig. 1, I designates the paper which is un wound from the roll 2. This paper runsover two rolls 3 and 4 and over the roll" 5 which is pulled 5' down bya helical spring 6 and is pivoted in a lever l movable around the point 8. At the other end of the lever 1 is one end of a wire 9 fastened and this wire is wound around a roll ID on the shaft of the regulating resistance I2. The other 10' end of the wire 9 is fastened to a 'helidal sprin II which acts in a direction opposite t that the spring 6 so that the wire 9 is always stretched. The rolls 3 and 4 are each coupled with the tachometer generators I3 and M which are excited from a cons nt direct current source.

The roll 2 is attached to a shaft l5 towhich is coupled'a th -phase commutatormotor with speed regulati by brush displacement. This motor is on the drawing designated by l6, and I1 is a tooth rim which is connected with the bridge carrying the brushes. Withathls tooth rim ens gages a pinion l8 which is attached-to a shaft which shaft also is connected with the counter regulation generator 20.

.The two tachometer generators l3 and I4 ar coupled in series but so that they counteract each other and are in series with a part of the resistance l2 connected to the coil 2| of the rapid regulator 22. This consists of a balance 23 which is pivoted -on an edge and is held in balance by two helical springs 25. The balance carries an arm 26 which carries two contacts 21 and 28 coacting with the stationary contacts 29 and 30.

The coil 2| as well as thecounter regulation coil 3| move in the air gaps of the permanent magnets 32 and 33 respectively. The contact pairs 7 29 and 3B are in.,cro ss connection connected to a source of constant voltage and the contacts 21 and '28 are connected with the terminals of the brush displacement motor. l3.

The counter regulation coil 3| is in series with the counter regulating generator 20 .connected with a re'gfilable inductance coil 34 and the contact arm 35 -of this-coil is connected with a roll 3B which rests against the surface of the paper roll 2.

As long as the stress in the paper I isconstant the balance 23 of the ,rapid regulator 22 swings around its zero position and the brush displacement motor I! receives lover the contacts 21 and 28 equal long current impulses for the motion the brush bridge I! is maintained and the motor l6 runs with constant speed and constant torque. If due to any cause the speed of the printing press should be altered the roll 5 moves upwards or downwards with a certain speed and this motion is a direct measure of the change'of the stress in the paper. Due to its inertia. the roll 2 at the beginning of the regulation can not change its speed and the speed of the roll 3 will therefore at the beginning remain constant whereas the speed of the roll 4 already from the beginning of the regulation will change its speed in accordance with the speed of the paper press. There will thus be a voltage difference be-' tween the two tachometer generators l3 and I4 and this voltage difference is added to the voltage drop over the resistance I2. The coil 2| on the regulator 22 will therefore be traversed by a current which on one hand is dependent on the position of the roll 5 and on the other hand on the difierence in speed between the rolls 3 and 4. Due to the change in the current through the coil 2i the balance 23 of the regulator 22 will swing around another mean value so that the brush displacement motor receives impulses for driving the brush bridge connected with the tooth rim H in the one or the other direction and the speed of the machine I6 is then changed so that the speed of the paper unwound from-the roll 2 becomes the same as the speed of the paper running through the press. When the speed of the printing press is constant the machine 16 is so regulated that the stress in the paper remains constant.

In order to avoid an over-regulation the brush displacement motor IS in previously known manner is connected with a small generator 20 which gives a current through the coil 3| in the rapid regulator 22 which current is proportional to the speed of the brushdisplacement. Inorder that the regulation may be entirely free from hunt-- ing the recalling achieved by means of the coil 3|, however, must be in a certain relation to the inertia of the system to beregulated, i. e. the inertia of the motor [6 and the roll.2.

If the roll 2 decreases in size the current through the regulating coil 3| thus must decrease in the same manner and this variation is achieved by means of the inductance 34, which due to the fact'that its contact arm 35 with one end rests against the surface of the roll2 to a large or smaller extent is inserted in the circuit of the coil 3|.

In the diagram Fig. 2 the operation of the hitherto known arrangements is shown, i. e. when ,the braking machine only is regulated with respect to the stress in the paper. It is assumed thatthe press is stopped on the point P1. Due to its inertia it can not stop immediately, but only after 10 to 15 seconds which time on the diagram is represented by the distance between the'points P1 and P2. During this time the speed and rapid regulation the roll 5 must move a certain fway before the regulationsof the machine It can commence and this takes place at first at the point P3 and then the speed V2 of the paper unwound from the roll is changed along a line shown by the line V: on the diagram. First when the line V2 intersects the line V1, at point P4, the

roll 2 has been retarded so much that its perif-- J press without any disadvantages shall be'able to be stopped in the above mentioned short time which with respect to the service may be necessary, it is necessary that the regulation is such that no assembling of paper in front of the press takes place. According to the invention such a regulation is achieved thereby that the braking machine is regulated not only with respect to the stress in the paper but also with respect to the diflerence between the speed of the paper in the press and the surface speed of the paper of the roll. The operation of such a regulation is illustrated in Fig. 3. 1n the diagram Fig. 3 the points P1X and P2X correspond to the points P1 and P2 of Fig. 2 while the lines Vlx and V2): correspond to the lines V1 and V2 of Fig: 2, and S1 designates the motion of the roll 5. As the regulator of the machine IS in this arrangement is actuated by a quantity which is proportional to the sum of the motion of the roll 5 and the speed diiference between the two paper webs, .i. e. the webin the press and the web unwound from the roll' 2, the regulation will commence at a much earlier stage at the point designated by P5. As seen from the diagram equality in speed between the two paper speeds is reached at a much earlier stage due to the fact that the regulating of machine l6 commences much earlier. Equality in speed is reached at the point P6. The amount of paper assembled in the frontpf the press will thus be much smaller and by an overregulation the paper can be reached by the present invention that no paper at all is assembled in front of the press, the roll 5 moving downwards only a little and the stress in the paper will be practically constant all the time.

fWe claim as our invention: 1. In a rotary printing press or other machine,

a web of a. ribbonor wire-formed material run-" ning through the machine, a reel from which the web is unwound, an electric generator coupled to" the reel and braking the reel, two stationary lead rollers, a movable lead roller arranged between said stationary rollers, a regulator controlling saidbraking generator, means for actuating said regulator in accordance with the diiference in speed of said stationary rollers, means for actuating said regulator in dependposition of said movable roller.

2. In a rotary printing press or other machine, a web of a ribbonor wire-formed material running through the machine, a reel from which the web is unwound, an electric generator coupled to the reel for braking it, two stationary lead rollers, two tachometer generators coupled to said rollers, a movable lead roller arranged between said stationary rollers, a spring actuating said movable lead roller, a resistance varied by said movable lead roller, a regulator controlling said ence of the stress in the web measured by the 1 braking generator, said regulator being actuated by the voltage difference between said tachometer generators and the voltage drop over the resistance actuated by the movable roller.

3. In a rotary printing press or similar machine, a web of a ribbonor wire-formed mate,- rial, a reel from which the web is unwound, an electric generator coupled to the reel for braking it, two stationary lead rollers, two tachometer generators coupled to said lead rollers, a mo'vable lead roller arranged between said stationary rollers, a resistance varied by said movable lead roller, a regulator controlling a speed regulation device on said braking generator, a counter regulation generator coupled to said 'speed regulat ing device, a regulable resistance inserted in series of the counter regulation generator, said resistance being varied by a lever resting with one end on the surface of the reel, the said regulator being actuated by the voltage difference of the two tachometer generators. the voltage drop over the resistance coupled to the movable roller, the voltage of the counter regulation generator, and

the voltage drop over the resistance varied by 10- the lever resting on the surface or the reel.

KARL GUSTAV Trams.- ms J. E. manor. 

